The present invention relates to an improved solar collector having a tube construction in which the tubes of the solar collector are intermittently separated along their length.
An important application of solar collectors is as part of a heating system for swimming pools. Most conventional low temperature pool heating solar collectors have an all-plastic construction which includes an extruded plastic absorber section containing hollow tubes connected to hollow manifolds on opposed absorber section ends. These absorber sections are conventionally either of tube mat or loose tube form. Tube mat collectors maintain uniform tube spacing either due to webs or spacers between adjacent hollow tubes or because adjacent tubes are connected directly to one another. Loose tube collectors require a plurality of spacer bars or clips intermittently positioned along their length to maintain tube spacing. Tube mat collectors provide a superior aesthetic and energy collection performance over loose tube collectors.
Solar collectors for swimming pool heating systems are typically mounted in an elevated location such as on top of a house roof. Such locations require the solar collector to be continuously exposed to the elements, and thus the solar collector must be sufficiently durable to withstand severe weather conditions, including wind, rain and hail.
Conventional loose tube collectors allow wind to freely pass through their very open absorber sections. This type of solar energy collector suffers from reduced solar energy collection capability in comparison to tube mat solar energy collectors due to the free and uninhibited passage of air around their absorber tube surfaces, which causes thermal energy loss due to convective cooling of the hollow tubes. Moreover, their energy collection capability proportionately worsens with increasing wind speed.
Conventional tube mat collectors have a 95-100% closed absorber section. The amount of air flow around the hollow tubes is minimized, and thus reduces convective heat loss.
Conventional tube mat solar energy collectors typically have a 4 foot width and a length of from 6 to 20 feet. A disadvantage of this closed absorbed section is the effect high winds can have on the solar collector, which can act as a sail. More particularly, high winds can exert very high force on the solar energy absorber, which force is transmitted to attachment hardware such as lag screws which secure the solar collector to the roof. Winds of sufficiently high velocity, for example, 15 miles per hour or above, can damage and even remove or otherwise destroy roof-mounted tube mat solar collectors. The industry has sought to overcome the problem of wind damage by using more mounting hardware than required by loose tube collectors. However, the use of additional mounting hardware increases the cost of material and labor, and requires an undesirable increase in the number of penetrations into a homeowner's roof.
An object of the present invention is to retain the superior solar energy collecting performance and aesthetic appeal of a tube mat solar collector in the most frequently encountered operating circumstances of low to moderate winds, while providing a lifting force reduction when acted upon by high winds.
A feature of the present invention is the presence of alternating separated and non-separated segments in a tube mat solar collector.
An advantage of the present invention is a reduction in lifting force exerted upon the mounting means securing the solar collector to its mounting location during periods of high velocity wind.